Hrm. I personally find myself trying to gender people "because it's societally correct as I was raised" (and am now trying to train myself out of this leftover from the 4th grade "oh shit" moment when I suddenly realized how much was going on around me that I had no clue about) --- but at the same time, insofar as it's a social / societal construct to some extent, I end up using a lot of rules of thumb. (And often getting reminded the hard way that the most appropriate "rule of thumb" in this case is that I'm prone to hit it with a hammer....)